A method for reducing CO2 to CO using a carbon-based molybdenum carbide heterojunction catalyst
By preparing a MoC-Mo2C heterocrystalline molybdenum carbide catalyst, the problems of high cost and single crystal phase in traditional methods were solved, and the efficient conversion and stability of CO2 hydrogenation to CO were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INST OF CHEM IND OF FOREST PROD CHINESE ACAD OF FORESTRY
- Filing Date
- 2026-03-20
- Publication Date
- 2026-07-03
Smart Images
Figure CN122324809A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of CO2 reduction technology, specifically relating to a method for reducing CO2 to prepare CO using a carbon-based molybdenum carbide heterojunction catalyst. Background Technology
[0002] The hydrogenation of carbon dioxide (CO2) to carbon monoxide (CO) is one of the important pathways for the resource conversion and utilization of CO2. It converts captured CO2 into CO, which can then be used to produce high-value-added chemicals and energy such as olefins and alcohols through Fischer-Tropsch synthesis and oxygen-containing compound synthesis. Transition metal carbides (TMCs), especially molybdenum carbide catalysts, exhibit noble metal-like catalytic behavior to some extent due to their unique electronic structure and surface adsorption characteristics. They possess advantages such as relatively low cost, good high-temperature stability, and strong resistance to poisoning, showing good application potential in CO2 hydrogenation reactions. Meanwhile, the crystal phase and composition of molybdenum carbides have a significant impact on the reaction pathway and product selectivity: different crystal phases of Mo... x C often exhibits different CO2 activation capabilities and intermediate adsorption characteristics, resulting in a differentiated tendency between the CO generation pathway and the oxygen-containing product generation pathway in the reverse water-gas shift reaction.
[0003] Traditional carburizing reduction processes for preparing molybdenum carbide require the introduction of large amounts of carbon-containing gases (methane, ethane, ethylene, etc.) and reducing gases such as hydrogen. This results in high costs, significant gas waste, difficult tail gas treatment, and substantial safety hazards. Furthermore, it can only produce single-phase products (such as α-MoC and β-Mo2C), thus affecting the space-time conversion rate and stability of CO2 hydrogenation to CO. Therefore, there is an urgent need to develop a simple process that does not require the introduction of additional carbon-containing and reducing gases and allows for the directional control of heterogeneous phases in molybdenum carbide preparation. Summary of the Invention
[0004] One technical problem solved by this invention is to provide a method for reducing CO2 to prepare CO using a carbon-based molybdenum carbide heterojunction catalyst, wherein the molybdenum carbide in the catalyst has a MoC-Mo2C heterojunction phase, thereby improving the space-time conversion rate and stability of CO2 to CO by hydrogenation.
[0005] Technical Solution: To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0006] A method for preparing CO by reducing CO2 using a carbon-based molybdenum carbide heterojunction catalyst involves adding the carbon-based molybdenum carbide heterojunction catalyst to a reactor, introducing H2 and CO2, and preparing CO. The catalyst comprises a carbon support and molybdenum carbide nanoparticles supported on the carbon support. The crystal phase of the molybdenum carbide is a MoC-Mo2C heterojunction phase.
[0007] The method for reducing CO2 to prepare CO using a carbon-based molybdenum carbide heterojunction catalyst involves preparing the catalyst using carbon and molybdenum sources as raw materials through ball milling, aging, and inert gas controlled flow and temperature calcination.
[0008] The method for reducing CO2 to prepare CO using a carbon-based molybdenum carbide heterojunction catalyst includes a calcination temperature of 700-900℃, an inert atmosphere of nitrogen or argon, and a calcination time of 2-4 h; the inert atmosphere flow rate is 150-250 mL / min; preferably, the calcination temperature is 700-800℃, the inert atmosphere is nitrogen or argon, the calcination time is 3 h, and the inert atmosphere flow rate is 200 mL / min; more preferably, the calcination temperature is 700℃.
[0009] The method for preparing CO by reducing CO2 using a carbon-based molybdenum carbide heterojunction catalyst, wherein the carbon source is one or more of glucose, fructose, sucrose, starch, cellulose, or hemicellulose; preferably, the carbon source is glucose; the molybdenum source is one or more of ammonium molybdate, sodium molybdate, potassium molybdate, or phosphomolybdic acid, preferably ammonium molybdate; the mass ratio of the molybdenum source to the carbon source is 1:2-1:3, preferably 1:2-1:2.5; more preferably, the mass ratio is 1:2, and all the above mass ratios are calculated based on the mass of ammonium molybdate and glucose.
[0010] The method for preparing CO by reducing CO2 using a carbon-based molybdenum carbide heterojunction catalyst includes ball milling, which is performed mechanically. The ball milling equipment is any one of a planetary ball mill, a drum ball mill, a vibratory ball mill, a stirred ball mill, a pendulum ball mill, or a sand mill. The ball milling time is 5-9 hours, and the ball milling speed is 300-600 r / min. Preferably, the ball milling time is 6 hours, and the speed is 400 r / min.
[0011] The method for reducing CO2 to prepare CO using a carbon-based molybdenum carbide heterojunction catalyst includes an aging atmosphere of air, nitrogen, and / or argon, an aging temperature of 100-150 °C, and an aging time of 10-14 h; preferably, the aging atmosphere is air, the temperature is 120 °C, and the time is 12 h.
[0012] The method for preparing CO by reducing CO2 using a carbon-based molybdenum carbide heterojunction catalyst is described, wherein CO is prepared at 450-550 °C, a volume ratio of H2 to CO2 of 2:1-4:1, a space velocity of 200,000-400,000 mL / g / h, and a pressure of 0.05-0.15 MPa; preferably, CO is prepared at 500 °C, a volume ratio of H2 to CO2 of 2:1, a space velocity of 300,000 mL / g / h, and a pressure of 0.1 MPa.
[0013] The method for preparing CO by reducing CO2 using a carbon-based molybdenum carbide heterojunction catalyst includes the following steps:
[0014] (1) Add ammonium molybdate and glucose into a ball mill and mechanically mix at 400 r / min for 6 h;
[0015] (2) The mechanically ball-milled mixture was aged in static air at 120 °C for 12 h;
[0016] (3) The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 700-800 °C and 200 mL / min nitrogen flow rate for 3 h to prepare the catalyst.
[0017] (4) Add the catalyst prepared in step (3) into a fixed-bed reactor to react and prepare CO.
[0018] The method for preparing CO by reducing CO2 using a carbon-based molybdenum carbide heterojunction catalyst has the following characteristics: the mass ratio of ammonium molybdate to glucose is 1:2-1:2.5; the calcination temperature is 700 ℃; preferably, the mass ratio of ammonium molybdate to glucose is 1:2.
[0019] The method for preparing CO by reducing CO2 using a carbon-based molybdenum carbide heterojunction catalyst prepares CO under the following conditions: 500 °C, H2 to CO2 volume ratio of 2:1, space velocity of 300000 mL / g / h, and pressure of 0.1 MPa.
[0020] Beneficial effects: Compared with the prior art, the present invention has the following advantages:
[0021] This invention uses carbon and molybdenum sources as raw materials to prepare carbon-based molybdenum carbide catalysts through in-situ carburizing activation via ball milling, aging, and inert atmosphere calcination, without the need for additional carbon-containing gas and reducing gas.
[0022] By adjusting the inert atmosphere flow rate and calcination temperature during the pyrolysis process, the control between the MoO2-MoC mixed crystalline phase, the pure MoC crystalline phase, and the MoC-Mo2C heterocrystalline phase can be achieved.
[0023] The reduction of CO2 to CO using a carbon-based MoC-Mo2C heterojunction catalyst exhibits excellent space-time conversion rate and stability, with a conversion rate exceeding 27% and a space-time conversion rate exceeding 33%. -5 molCO2 / g cat / s. Attached Figure Description
[0024] Figure 1 The X-ray diffraction patterns are those of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 of this invention.
[0025] Figure 2 These are high-resolution transmission electron microscope (TEM) images of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 of this invention.
[0026] Figure 3 This is a graph showing the stability evaluation results of the catalyst prepared in Example 4 of the present invention. Detailed Implementation
[0027] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.
[0028] Example 1
[0029] Weigh out ammonium molybdate and glucose (mass ratio 1:3) and add them to a ball mill jar. Mix mechanically at 400 r / min for 6 h.
[0030] The mixture after mechanical ball milling was aged at 120 °C in static air for 12 h.
[0031] The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 700 °C and a nitrogen flow rate of 200 mL / min for 3 h to prepare the Mo-AC-1 catalyst.
[0032] The molybdenum carbide in this catalyst is a MoC-Mo2C heterocrystalline phase with an average particle size of 3.29 nm (e.g., Figure 1 and Figure 2 (As shown).
[0033] Comparative Example 1
[0034] Weigh out ammonium molybdate and glucose (mass ratio 1:3) and add them to a ball mill jar. Mix mechanically at 400 r / min for 6 h.
[0035] The mechanically ball-milled mixture was aged at 120 °C in static air for 12 h;
[0036] The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 700 °C and a nitrogen flow rate of 10 mL / min for 3 h to prepare the Mo-AC-2 catalyst.
[0037] The molybdenum in this catalyst is a mixed MoO2-MoC crystalline phase with an average particle size of 3.75 nm (e.g., Figure 1 and Figure 2 (As shown).
[0038] Comparative Example 2
[0039] Weigh out ammonium molybdate and glucose (mass ratio 1:3) and add them to a ball mill jar. Mix mechanically at 400 r / min for 6 h.
[0040] The mechanically ball-milled mixture was aged at 120 °C in static air for 12 h;
[0041] The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 650 °C and a nitrogen flow rate of 200 mL / min for 8 h to prepare the Mo-AC-3 catalyst.
[0042] The molybdenum carbide in this catalyst is a pure MoC crystalline phase with an average particle size of 2.52 nm (e.g., Figure 1 and Figure 2 (As shown).
[0043] Example 2
[0044] Weigh out ammonium molybdate and glucose (mass ratio 1:3) and add them to a ball mill jar. Mix mechanically at 400 r / min for 6 h.
[0045] The mechanically ball-milled mixture was aged at 120 °C in static air for 12 h;
[0046] The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 800 °C and a nitrogen flow rate of 200 mL / min for 3 h to prepare the Mo-AC-4 catalyst.
[0047] The molybdenum carbide in this catalyst is a MoC-Mo2C heterocrystalline phase with an average particle size of 3.41 nm (e.g., Figure 1 and Figure 2 (As shown).
[0048] Example 3
[0049] Weigh out ammonium molybdate and glucose (mass ratio 1:3) and add them to a ball mill jar. Mix mechanically at 400 r / min for 6 h.
[0050] The mechanically ball-milled mixture was aged at 120 °C in static air for 12 h;
[0051] The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 900 °C and a nitrogen flow rate of 200 mL / min for 3 h to prepare the Mo-AC-5 catalyst.
[0052] The molybdenum carbide in this catalyst is a MoC-Mo2C heterocrystalline phase with an average particle size of 4.41 nm (e.g., Figure 1 and Figure 2 (As shown).
[0053] Comparative Example 3
[0054] Weigh out ammonium molybdate and glucose (mass ratio 1:3) and add them to a ball mill jar. Mix mechanically at 400 r / min for 6 h.
[0055] The mechanically ball-milled mixture was aged at 120 °C in static air for 12 h;
[0056] The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 1000 °C and a nitrogen flow rate of 200 mL / min for 3 h to prepare the Mo-AC-6 catalyst.
[0057] The molybdenum carbide in this catalyst is a MoC-Mo2C heterocrystalline phase with an average particle size of 5.49 nm (e.g., Figure 1 and Figure 2 (As shown).
[0058] Example 4
[0059] Weigh out ammonium molybdate and glucose (mass ratio 1:2) and add them to a ball mill jar. Mix them mechanically at 400 r / min for 6 h.
[0060] The mechanically ball-milled mixture was aged at 120 °C in static air for 12 h;
[0061] The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 700 °C and a nitrogen flow rate of 200 mL / min for 3 h to prepare the Mo-AC-7 catalyst.
[0062] The molybdenum carbide in this catalyst is a MoC-Mo2C heterocrystalline phase. Figure 3 The graph shows the stability evaluation results of the catalyst, indicating that the catalyst has very good stability.
[0063] Example 5
[0064] Weigh out ammonium molybdate and glucose (mass ratio 1:2.5) and add them to a ball mill jar. Mix mechanically at 400 r / min for 6 h.
[0065] The mechanically ball-milled mixture was aged at 120 °C in static air for 12 h;
[0066] The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 700 °C and a nitrogen flow rate of 200 mL / min for 3 h to prepare the Mo-AC-8 catalyst.
[0067] The molybdenum carbide in this catalyst is a MoC-Mo2C heterocrystalline phase.
[0068] Example 6
[0069] The catalysts prepared in Examples 1-5 and Comparative Examples 1-3 were loaded into micro fixed-bed reactors at 24 mg each. The space-time conversion rate and selectivity of the reaction were obtained under the conditions of 500 °C, H2 to CO2 volume ratio of 2:1, space velocity of 300000 mL / g / h, and pressure of 0.1 MPa. The results are shown in Table 1.
[0070] The reaction tail gas, after being heated to 150 °C, was analyzed online using a gas chromatograph (SHIMADZU GC-2014C), and the products were quantified using the external standard method. CO2 conversion rate (X...) CO2 CO selectivity (S) CO ) and the CO2 reaction space-time conversion rate normalized to catalyst mass (Rate) CO2 Calculate using the following formula:
[0071] (1);
[0072] (2);
[0073] (3).
[0074] In the formula, n CO,out n CO2,out With n CH4,out These represent the molar flow rates of CO, CO2, and CH4 in the reactor outlet gas, respectively; n CO,in F is the molar flow rate of CO2 in the feed. CO2 The feed molar flow rate of CO2; m cat This refers to the catalyst loading mass.
[0075] Table 1. Space-time conversion rate and selectivity of CO2 catalytic hydrogenation to CO.
[0076]
[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for producing CO by reduction of CO2 using a carbon-based molybdenum carbide heterojunction catalyst, characterized by, A carbon-based molybdenum carbide heterojunction catalyst is added to a reactor, and H2 and CO2 are introduced to reduce CO2 to prepare CO; the crystal phase of the molybdenum carbide is MoC-Mo2C heterojunction.
2. The method of claim 1, wherein, The catalyst is prepared by using carbon and molybdenum sources as raw materials, through ball milling for uniform mixing, aging, and inert gas controlled flow and temperature calcination.
3. The method of claim 2, wherein, The calcination temperature is 700-900 ℃, the inert atmosphere is nitrogen or argon, the calcination time is 2-4 h, and the inert atmosphere flow rate is 150-250 mL / min.
4. The method of claim 2, wherein, The carbon source is one or more of glucose, fructose, sucrose, starch, cellulose, or hemicellulose; the molybdenum source is one or more of ammonium molybdate, sodium molybdate, potassium molybdate, or phosphomolybdic acid; and the mass ratio of the molybdenum source to the carbon source is 1:2 to 1:
3.
5. The method of claim 2, wherein, The ball milling is a mechanical ball milling, with a milling time of 5-9 hours and a milling speed of 300-600 r / min.
6. The method of claim 2, wherein, The aging temperature is 100-150 ℃, the aging time is 10-14 h, and the aging atmosphere is air, nitrogen and / or argon.
7. The method of claim 1, wherein, CO was prepared at 450-550 °C, with a volume ratio of H2 to CO2 of 2:1-4:1, a space velocity of 200,000-400,000 mL / g / h, and a pressure of 0.05-0.15 MPa.
8. The method of claim 1, wherein, Includes the following steps: (1) Add ammonium molybdate and glucose to a ball mill and mechanically mix at 400 r / min for 6 h; (2) The mechanically ball-milled mixture was aged in static air at 120 °C for 12 h; (3) The aged sample was placed in a tube furnace, and after the air in the tube furnace was removed, it was calcined at 700-800 °C and 200 mL / min nitrogen flow rate for 3 h to prepare the catalyst. (4) Add the catalyst prepared in step (3) into a fixed-bed reactor to react and prepare CO.
9. The method of claim 8, wherein, The mass ratio of ammonium molybdate to glucose is 1:2 to 1:2.5, and the calcination temperature is 700 ℃.
10. The method of claim 1 or 8, wherein, CO was prepared at 500 °C, with a volume ratio of H2 to CO2 of 2:1, a space velocity of 300,000 mL / g / h, and a pressure of 0.1 MPa.